He entered the NFL as a line judge in 1995, and later was promoted to referee in 1998 after Dale Hamer returned to the head linesman position and Gary Lane returned to the side judge position.

In his first playoff assignment as a referee, Winter refereed the New York Giants and San Francisco 49ersWild Card playoff game in January, 2003. In this game, back judge Scott Green did not realize that New York's Rich Seubert had lined up legally in a receiver's spot and failed to call a defensive pass interference foul against him during a failed field goal attempt, instead penalizing him for ineligible receiver downfield. Commissioner Paul Tagliabue described the situation as the most disappointing officiating blunder he'd seen in his years as NFL commissioner[3] and announced that officiating mechanics surrounding field-goal attempts and last plays of games would be changed.[4]